Volume Swapping of Point-In-Time Read-Only Target Volumes

ABSTRACT

A mechanism is provided for adding point-in-time copy relationships to a data processing system. A request is received to establish a first point-in-time copy relationship. Responsive to determining that a first target of the first point-in-time copy relationship is target write inhibited, that a source of the first point-in-time copy relationship is a source of a first continuous synchronous copy relationship, that a target of the first continuous synchronous copy relationship is part of a second point-in-time copy relationship, and that the source of the first point-in-time copy relationship is part of a volume swap configuration, a volume swap relationship is added between the first point-in-time target volume and the second point-in-time target volume to the volume swap configuration. Both point-in-time copy relationships are established and any continuous synchronous copy requirements of the volume swap relationship between the first point-in-time target volume and the second point-in-time target volume are disabled.

BACKGROUND

The present application relates generally to an improved data processingapparatus and method and more specifically to mechanisms for volumeswapping point-in-time read-only target volumes.

In known data processing systems, instantaneous point-in-time copyrelationships may be established between a source volume and a targetvolume. At the time the instantaneous point-in-time relationship isestablished, the data processing system may atomically establish asecond instantaneous point-in-time relationship between a continuoussynchronous copy volume associated with the source volume and anothertarget volume as well as establishing another continuous synchronouscopy relationship between the target volumes. However, establishing bothcontinuous synchronous copy relationships between the source volume andthe continuous synchronous copy volume as well as between the targetvolumes requires significant set-up time, additional resources on andbetween the storage system, additional planning and monitoring by theoperator (or application), additional bandwidth for the continuoussynchronous copy paths, or the like. Further, additional storage systemresources include the additional connections (paths) to copy the dataand the additional bandwidth over the connections to complete a fullcopy of the target volumes. If the paths to copy the data are not directconnections, additional switching resources may also be required. As theinstantaneous point-in-time copies may only be initiated when thecontinuous copy relationships are in a full duplex state, additionalwork is required to monitor the continuous copy relationships prior toinitiating the instantaneous point-in-time copies.

SUMMARY

In one illustrative embodiment, a method, in a data processing system,is provided for adding point-in-time copy relationships to the dataprocessing system. The illustrative embodiment receives a request toestablish a first point-in-time copy relationship. The illustrativeembodiment adds a volume swap relationship between the firstpoint-in-time target volume and the second point-in-time target volumeto the volume swap configuration in response to determining that a firsttarget of the first point-in-time copy relationship is target writeinhibited, determining that a source of the first point-in-time copyrelationship is a source of a first continuous synchronous copyrelationship, determining that a target of the first continuoussynchronous copy relationship is either a source of an alreadyestablished second point-in-time copy relationship or an intended sourceof the second point-in-time copy relationship, and determining that thesource of the first point-in-time copy relationship is part of a volumeswap configuration. The illustrative embodiment establishes bothpoint-in-time copy relationships in the data processing system. Theillustrative embodiment disables any continuous synchronous copyrequirements of the volume swap relationship between the firstpoint-in-time target volume and the second point-in-time target volume.

In other illustrative embodiments, a computer program product comprisinga computer useable or readable medium having a computer readable programis provided. The computer readable program, when executed on a computingdevice, causes the computing device to perform various ones, andcombinations of, the operations outlined above with regard to the methodillustrative embodiment.

In yet another illustrative embodiment, a system/apparatus is provided.The system/apparatus may comprise one or more processors and a memorycoupled to the one or more processors. The memory may compriseinstructions which, when executed by the one or more processors, causethe one or more processors to perform various ones, and combinations ofthe operations outlined above with regard to the method illustrativeembodiment.

These and other features and advantages of the present invention will bedescribed in, or will become apparent to those of ordinary skill in theart in view of, the following detailed description of the exampleembodiments of the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention, as well as a preferred mode of use and further objectivesand advantages thereof, will best be understood by reference to thefollowing detailed description of illustrative embodiments when read inconjunction with the accompanying drawings, wherein:

FIG. 1 depicts a pictorial representation of an example distributed dataprocessing system in which aspects of the illustrative embodiments maybe implemented;

FIG. 2 shows a block diagram of an example data processing system inwhich aspects of the illustrative embodiments may be implemented;

FIGS. 3A and 33 depict an example of a continuous synchronous copyrelationship between two storage volumes in accordance with anillustrative embodiment;

FIGS. 4A and 43 depict an example of a point-in-time copy relationshipbetween two storage volumes in accordance with an illustrativeembodiment;

FIGS. 5A-5C depict an example of an existing volume swapping environmentthat uses both continuous synchronous copy and point in time copyrelationships in accordance with an illustrative embodiment;

FIGS. 6A and 6B depict an example of volume swapping environment thatutilizes a copy services manager to recognize that the source volume andtarget volume of a continuous synchronous copy relationship are bothsources of respective pending point-in-time copy relationships that willbe target write inhibited in accordance with an illustrative embodiment;

FIG. 7 depicts a flowchart outlining example operations performed by acopy services manager in adding point-in-time copy relationships to adata processing system in accordance with an illustrative embodiment;and

FIG. 8 depicts a flowchart outlining example operations performed by acopy services manager in withdrawing point-in-time copy relationships toa data processing system in accordance with an illustrative embodiment.

DETAILED DESCRIPTION

The illustrative embodiments provide a mechanism for changing currentimplementations for volume swapping from a source volume to a targetvolume, such as the service provided by HyperSwap®, to have a copyservices manager recognize that the source volume and target volume of asynchronous continuous copy relationship are both sources of respectivepending point-in-time copy relationships, such as the service providedthrough FlashCopy®. With this knowledge, the copy services manager willadd the point-in-time copy target volumes into the volume swappingconfiguration and pass the new configuration to either a Input/OutputSupervisor (IOS) in a z/OS® system, a device driver in a AIX® system, orthe like, when establishing the point-in-time copy relationships. Usingthe new configuration may make a point-in-time copy target eligible fora volume swapping operation. When the point-in-time copy relationshipsare withdrawn, the copy services manager will load a new configurationthat has the point-in-time copy target volume removed making the volumesno longer volume swapping capable.

HyperSwap® for z/OS® systems and HyperSwap® for ALX® systems (also knownas Open HyperSwap®) provide a storage system high availability functionthat will switch input/output (I/O) requests from a source volume of asynchronous continuous copy to a target volume of the synchronouscontinuous copy without having to restart applications using the sourcevolume. HyperSwap® may be initiated by command or as a result of apermanent input/output (I/O) failure when reading from or writing to thesource volume. The set of continuous copy volumes and their role in thecopy is passed to a Input/Output Supervisor (IOS) (z/OS®) or a devicedriver (AIX®). This configuration is then saved for later use by the IOSor the device driver to execute the HyperSwap®.

FlashCopy® is a point-in-time copy that will save a copy of data on atarget volume as it exists on a source volume at the time the flash copyrelationship was established and the copy initiated. The source andtarget volume may be independently updated at any time after theestablishment. Many FlashCopy® relationships are created where thetarget volume is not updated or should never be updated. For thesecases, the FlashCopy® relationship is established with a ‘target writeinhibited’ option. These copies may be used for making backups or forbatch processing checkpoints.

Thus, the illustrative embodiments may be utilized in many differenttypes of data processing environments including a distributed dataprocessing environment, a single data processing device, or the like. Inorder to provide a context for the description of the specific elementsand functionality of the illustrative embodiments, FIGS. 1 and 2 areprovided hereafter as example environments in which aspects of theillustrative embodiments may be implemented. While the descriptionfollowing FIGS. 1 and 2 will focus primarily on a single data processingdevice implementation of a mechanism that volume swaps point-in-timeread-only target volumes, this is only an example and is not intended tostate or imply any limitation with regard to the features of the presentinvention. To the contrary, the illustrative embodiments are intended toinclude distributed data processing environments and embodiments inwhich point-in-time read-only target volumes are volume swapped.

With reference now to the figures and in particular with reference toFIGS. 1-2, example diagrams of data processing environments are providedin which illustrative embodiments of the present invention may beimplemented. It should be appreciated that FIGS. 1-2 are only examplesand are not intended to assert or imply any limitation with regard tothe environments in which aspects or embodiments of the presentinvention may be implemented. Many modifications to the depictedenvironments may be made without departing from the spirit and scope ofthe present invention.

With reference now to the figures. FIG. 1 depicts a pictorialrepresentation of an example distributed data processing system in whichaspects of the illustrative embodiments may be implemented. Distributeddata processing system 100 may include a network of computers in whichaspects of the illustrative embodiments may be implemented. Thedistributed data processing system 100 contains at least one network102, which is the medium used to provide communication links betweenvarious devices and computers connected together within distributed dataprocessing system 100. The network 102 may include connections, such aswire, wireless communication links, or fiber optic cables.

In the depicted example, server 104 and server 106 are connected tonetwork 102 along with storage units 108 and 116. In addition, clients110, 112, and 114 are also connected to network 102. These clients 110,112, and 114 may be, for example, personal computers, network computers,or the like. In the depicted example, server 104 provides data, such asboot files, operating system images, and applications to the clients110, 112, and 114. Clients 110, 112, and 114 are clients to server 104in the depicted example. Distributed data processing system 100 mayinclude additional servers, clients, and other devices not shown.

In the depicted example, distributed data processing system 100 is theInternet with network 102 representing a worldwide collection ofnetworks and gateways that use the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, consisting of thousands of commercial, governmental,educational and other computer systems that route data and messages. Ofcourse, the distributed data processing system 100 may also beimplemented to include a number of different types of networks, such asfor example, an intranet, a local area network (LAN), a wide areanetwork (WAN), or the like. As stated above, FIG. 1 is intended as anexample, not as an architectural limitation for different embodiments ofthe present invention, and therefore, the particular elements shown inFIG. 1 should not be considered limiting with regard to the environmentsin which the illustrative embodiments of the present invention may beimplemented.

With reference now to FIG. 2, a block diagram of an example dataprocessing system is shown in which aspects of the illustrativeembodiments may be implemented. Data processing system 200 is an exampleof a computer, such as client 110 or server 104 in FIG. 1, in whichcomputer usable code or instructions implementing the processes forillustrative embodiments of the present invention may be located.

In the depicted example, data processing system 200 employs a hubarchitecture including north bridge and memory controller hub (NB/MCH)202 and south bridge and input/output (I/O) controller hub (SB/ICH) 204.Processing unit 206, main memory 208, and graphics processor 210 areconnected to NB/MCH 202. Graphics processor 210 may be connected toNB/MCH 202 through an accelerated graphics port (AGP).

In the depicted example, local area network (LAN) adapter 212 connectsto SB/ICH 204. Audio adapter 216, keyboard and mouse adapter 220, modem222, read only memory (ROM) 224, hard disk drive (HDD) 226, CD-ROM drive230, universal serial bus (USB) ports and other communication ports 232,and PCI/PCIe devices 234 connect to SB/ICH 204 through bus 238 and bus240. PCI/PCIe devices may include, for example, Ethernet adapters,add-in cards, and PC cards for notebook computers. PCI uses a card buscontroller, while PCIe does not. ROM 224 may be, for example, a flashbasic input/output system (BIOS).

HDD 226 and CD-ROM drive 230 connect to SB/ICH 204 through bus 240. HDD226 and CD-ROM drive 230 may use, for example, an integrated driveelectronics (IDE) or serial advanced technology attachment (SATA)interface. Super I/O (SIO) device 236 may be connected to SB/ICH 204.

An operating system runs on processing unit 206. The operating systemcoordinates and provides control of various components within the dataprocessing system 200 in FIG. 2. As a client, the operating system maybe a commercially available operating system such as Microsoft® Windows®XP (Microsoft and Windows are trademarks of Microsoft Corporation in theUnited States, other countries, or both). An object-oriented programmingsystem, such as the Java™ programming system, may run in conjunctionwith the operating system and provides calls to the operating systemfrom Java™ programs or applications executing on data processing system200 (Java is a trademark of Sun Microsystems. Inc. in the United States,other countries, or both).

As a server, data processing system 200 may be, for example, an IBM®Power Systems, running the Advanced Interactive Executive (AIX®)operating system or the LINUX® operating system (Power Systems and AIXare trademarks of International Business Machines Corporation in theUnited States, other countries, or both while LINUX is a trademark ofLinus Torvalds in the United States, other countries, or both). Dataprocessing system 200 may be a symmetric multiprocessor (SMP) systemincluding a plurality of processors in processing unit 206.Alternatively, a single processor system may be employed.

Instructions for the operating system, the object-oriented programmingsystem, and applications or programs are located on storage devices,such as HDD 226, and may be loaded into main memory 208 for execution byprocessing unit 206. The processes for illustrative embodiments of thepresent invention may be performed by processing unit 206 using computerusable program code, which may be located in a memory such as, forexample, main memory 208, ROM 224, or in one or more peripheral devices226 and 230, for example.

A bus system, such as bus 238 or bus 240 as shown in FIG. 2, may becomprised of one or more buses. Of course, the bus system may beimplemented using any type of communication fabric or architecture thatprovides for a transfer of data between different components or devicesattached to the fabric or architecture. A communication unit, such asmodem 222 or network adapter 212 of FIG. 2, may include one or moredevices used to transmit and receive data. A memory may be, for example,main memory 208, ROM 224, or a cache such as found in NB/MCH 202 in FIG.2.

Those of ordinary skill in the art will appreciate that the hardware inFIGS. 1-2 may vary depending on the implementation. Other internalhardware or peripheral, devices, such as flash memory, equivalentnon-volatile memory, optical disk drives, or the like, may be used inaddition to or in place of the hardware depicted in FIGS. 1-2. Also, theprocesses of the illustrative embodiments may be applied to amultiprocessor data processing system without departing from the spiritand scope of the present invention.

Moreover, the data processing system 200 may take the form of any of anumber of different data processing systems including client computingdevices, server computing devices, a tablet computer, laptop computer,telephone or other communication device, a personal digital assistant(PDA), or the like. In some illustrative examples, data processingsystem 200 may be a portable computing device which is configured withflash memory to provide non-volatile memory for storing operating systemfiles and/or user-generated data, for example. Essentially, dataprocessing system 200 may be any known or later developed dataprocessing system without architectural limitation.

FIGS. 3A and 38 depict an example of a continuous synchronous copyrelationship between two storage volumes in accordance with anillustrative embodiment. As shown in the FIG. 3A, source volume 302 andtarget volume 304, which are part of the continuous synchronous copyrelationship, are in a full duplex state. A full duplex state occurswhen two volumes, source volume 302 and target volume 304, are in acontinuous synchronous copy relationship and both volumes have identicaldata. Both source volume 302 and target volume 304 are either attached,mounted, or the like, to server 306. When an application on server 306writes to source volume 302, that same data is written to target volume304 before control is returned to the application. Thus, the data ontarget volume 304 is the same as the data on source volume 302.

In FIG. 38, when an Input/Output Supervisor (IOS), device driver, or thelike, in server 306 receives a command or detects an error in writing toor reading from source volume 302, the IOS, device driver, or the like,initiates a volume swap. The IOS, device driver, or the like thendirects a storage controller associated with source volume 302 toterminate the continuous synchronous copy between source volume 302 andtarget volume 304 and the IOS, device driver, or the like, in server 306directs all subsequent I/O to target volume 304.

FIGS. 4A and 4B depict an example of a point-in-time copy relationshipbetween two storage volumes in accordance with an illustrativeembodiment. As is shown in FIG. 4A, a point-in-time copy relationship isestablished between source volume 402 and point-in-time (PIT) targetvolume 408. When server 406 initiates a point-in-time copy, data onsource volume 402 is copied to point-in-time target volume 408 as thedata existed at the time the point-in-time copy was initiated. Whenserver 406 initiates a new point-in-time copy, previous data onpoint-in-time target volume 408 is erased and the data as it exists atthe time the new point-in-time copy is initiated is copied topoint-in-time target volume 408.

In FIG. 4B, server 406 may use data on point-in-time target volume 408as a source for a backup operation, data mining, or the like. Using apoint-in-time copy operation in this way allows the application to bequiesced only for the time necessary to perform the point-in-time copyoperation, which is a fraction of the time necessary to write all of thedata of source volume 402 to another backup device, such as a backuptape, external drive, or the like.

FIGS. 5A-5C depict an example of an existing volume swapping environmentthat uses both continuous synchronous copy and point in time copyrelationships in accordance with an illustrative embodiment. FIGS. 5A-5Cdepict one example of a volume swapping configuration whether it be forreadable, writable, or readable/writable point-in-time copyrelationship, although all known volume swapping configurations that usea readable, writable, or readable/writable point-in-time copyrelationship required a continuous synchronous copy relationship betweenthe point-in-time target volumes. Thus, in the depicted volume swappingenvironment, the use of point-in-time copy relationships require thatsource volume 502 and target volume 504 be in a continuous synchronouscopy relationship and in a full duplex state as well as point-in-timetarget volumes 508 and 510 be in a continuous synchronous copyrelationship and in a full duplex state prior to establishment of thepoint-in-time copy relationship between source volume 502 andpoint-in-time target volume 508 and between target volume 504 andpoint-in-time target volume 510.

As shown in FIG. 5A, two continuous synchronous copy relationships areestablished between source volume 502 and target volume 504 and betweenpoint-in-time target volume 508 and point-in-time target volume 510.Once the continuous synchronous copy relationships are established,server 506 and/or a storage controller (not shown) may initiate a fullbackground copy of source volume 502 to target volume 504 and ofpoint-in-time target volume 508 to point-in-time target volume 510 sothat target volume 504 and point-in-time target 510 reach a full duplexstate with source volume 502 and point-in-time target volume 508,respectively.

In FIG. 58, once target volume 504 reaches a full duplex state withsource volume 502 and point-in-time target volume 510 reaches a fullduplex state with point-in-time target volume 508, point-in-time copyrelationships may be established between source volume 502 andpoint-in-time target volume 508. At the time the point-in-timerelationships are established, the server identifies whetherpoint-in-time target volume 508 and point-in-time target volume 510 willbe readable, writable, or readable/writable. With the establishment ofthe point-in-time relationship between source volume 502 andpoint-in-time target volume 508 will atomically establish apoint-in-time relationship between target volume 504 and point-in-timetarget volume 510. Any updates made to point-in-time target volume 508are also mirrored to point-in-time target volume 510 because of thecontinuous synchronous copy relationship between point-in-time targetvolume 508 and point-in-time target volume 510. Server 506 stores theestablished relationships as a volume swapping configuration. The volumeswapping configuration includes all of the volumes and their respectiveroles as all of the volume are in one or more continuous copyrelationships and/or point-in-time copy relationships.

In FIG. 5C, when an Input/Output Supervisor (IOS), device driver, or thelike, in server 506 receives a command or detects an error in writing toor reading from source volume 502 or point-in-time target volume 508,the IOS, device driver, or the like, initiates a volume swap. A storagecontroller associated with source volume 502, on its own or in responseto an explicit command from server 506, terminates the continuoussynchronous copy between source volume 502 and target volume 504 as wellas the continuous synchronous copy between point-in-time target volume508 and point-in-time target volume 510. The IOS, device driver, or thelike, in server 506 directs all subsequent I/O to target volume 504 andpoint-in-time target volume 510.

As is illustrated in FIG. 5B, the illustrated volume swapping methodrequires and establishes both a continuous synchronous copy ofpoint-in-time target volume 508 to point-in-time target volume 510 aswell as point-in-time copy of target volume 504 to point-in-time targetvolume 510. The requirements of the continuous synchronous copyrelationship between point-in-time target volume 508 and point-in-timetarget volume 510 requires significant set-up time and the establishmentof the continuous synchronous copy relationship. The establishment ofthe continuous synchronous copy relationship requires additionalresources on and between the storage system, additional planning andmonitoring by the operator (or application), additional bandwidth forthe continuous synchronous copy paths, or the like. Further, additionalstorage system resources include the additional connections (paths) tocopy the data and the additional bandwidth over the connections tocomplete a full copy of point-in-time target volumes 508 and 510. If thepaths to copy the data are not direct connections, additional switchingresources may also be required. As the point-in-time copy may only beinitiated when the continuous copy relationship is in a full duplexstate, additional work is required to monitor the continuous copyrelationships prior to initiating the point-in-time copy.

However, the continuous synchronous copy relationship as described inFIGS. 5A and 5B may not be necessary if the source volume 502 andpoint-in-time target volume 508 point-in-time copy are coordinated withthe target volume 504 and point-in-time target volume 510 point-in-timecopy and with both point-in-time copies are established with aninhibited target write on point-in-time target volume 508 andpoint-in-time target volume 510.

FIGS. 6A and 6B depict an example of volume swapping environment thatutilizes a copy services manager to recognize that the source volume andtarget volume of a continuous synchronous copy relationship are bothsources of respective pending point-in-time copy relationships that willbe target write inhibited in accordance with an illustrative embodiment.In FIG. 6A, source volume 602 and target volume 604 are established aspart of a continuous synchronous copy relationship and are set up in afull duplex state. That is, when application 612 on server 606 writes tosource volume 602, that same data is written to target volume 604 beforecontrol is returned to application 612. Thus, the data on target volume604 is the same as the data on source volume 602, which is considered afull duplex state. Both source volume 602 and target volume 604 arecoupled to server 606 either by attachment, mounting, or the like.

Once coupled to server 606, copy services manager (CSM) 614 adds bothsource volume 602 and target volume 604 as a volume swap relationship toa volume swap configuration that identifies the pair of volumes as acontinuous synchronous copy pair and that target volume 604 is thevolume to be swapped to if a command is received to perform a volumeswap operation or an error is detected writing to or reading from sourcevolume 602 such that a volume swap is performed.

If in addition to the establishment of the continuous synchronous copyrelationship between source volume 602 and target volume 604, there isalso request to establish one or a pair of point-in-time copyrelationships, copy services manager 614 determines whetherpoint-in-time target volume 608 associated with source volume 602 is acandidate for a non-continuous synchronous copy volume swaprelationship. Copy services manager 614 first determines whether thetargets of the point-in-time copy relationships, point-in-time targetvolumes 608 and 610, are target write inhibited. If point-in-time targetvolumes 608 and 610 of the point-in-time copy relationships are targetwrite inhibited, then copy services manager 614 determines whether thesource of the first point-in-time copy relationship, source volume 602,is a continuous synchronous copy source. Since source volume 602 of thepoint-in-time copy relationship is a continuous synchronous copy source,then copy services manager 614 determines whether the target of theaforementioned continuous synchronous copy, target volume 604, is eitherthe source of the already established second point-in-time copyrelationship or is intended to be a source of the second point-in-timecopy relationship. Since target volume 604 of the aforementionedcontinuous synchronous copy is the source or intended source of thesecond point-in-time copy relationship with point-in-time target volume610, then copy services manager 614 determines whether the source of thefirst point-in-time copy relationship, source volume 602, which is alsoa continuous synchronous copy source to target volume 604, is part ofthe volume swap configuration. That is, copy services manager 614determines if a volume swap relationship between source volume 602 andtarget volume 604, which matches the continuous synchronous copyrelationship between source volume 602 and target volume 604, exists inthe volume swap configuration.

Since source volume 602 is the source of the first point-in-time copyrelationship and is part of the volume swap configuration, then copyservices manager 614 adds the point-in-time copy relationship betweensource volume 602 and point-in-time target volume 608 as well as thepoint-in-time copy relationship between target volume 604 andpoint-in-time target volume 610 to the volume swap configuration. Addingthe point-in-time copy relationships to the volume swap configuration bycopy services manager 614 is purely for providing additional informationto IOS/device driver 616, as the point-in-time relationships are notused during a volume swap. By adding the point-in-time relationships tothe volume swap configuration, copy services manager 614 makesIOS/device driver 616 aware of the existence of the point-in-time copyrelationships and is therefore purely optional.

Copy services manager 614 then adds a volume swap relationship betweenpoint-in-time target volume 608 and point-in-time target volume 610 tothe volume swap configuration with a flag set indicating that the IOS,device driver, or the like, need not verify or monitor any continuoussynchronous copy requirements between point-in-time target volumes 608and 610. After the volume swap relationships have been added to thevolume swap configuration and prior to establishing both point-in-timecopy relationships, it is critical that point-in-time target volume 608and point-in-time target volume 610 have the same data. In order toensure that both volumes have the same data, when copy services manager614 establishes the point-in-time relationships, copy services manager614 specifies a point-in-time copy consistency group option. Thepoint-in-time consistency group option causes source volume 602 to belong busied while copy services manager 614 initiates a point-in-timecopy between source volume 602 and point-in-time target volume 608 aswell as a point-in-time copy between target volume 604 and point-in-timetarget volume 610. Even if copy services manager 614 initiates thepaint-in-time copy between target volume 604 and point-in-time targetvolume 610 first, the long busy is propagated back to the source volume602 because of the continuous synchronous copy relationship betweensource volume 602 and target volume 604.

Long busy is a condition where a storage controller temporarily preventsnew I/O to the storage controller by presenting a “busy” or“uninterruptable” condition. However, a long busy also indicates thatthe “busy” will be longer than normal. When IOS/device driver 616identifies a long busy, IOS/device driver 616 recognizes to hold I/Ountil the storage controller clears the uninterruptable condition. Bydoing this, the storage controller and/or CSM 614 has time to performother actions that must be completed before the particular device isaccessed again. In this example, a long busy provides CSM 614 with timeto initiate the point-in-time copy between source volume 602 andpoint-in-time target volume 608, and between target volume 604 andpoint-in-time target volume 610, knowing that source volume 602 andtarget volume 604 are identical copies of each other when theirrespective point-in-time copies were initiated. While the illustrativeembodiments use a long busy to prevent new I/O to the storagecontroller, the illustrative embodiments also recognize that otherconditions may also be used to prevent new I/O from going to the storagecontroller, such as pausing, stopping, shutting down an application, orthe like.

In addition to establishing the point-in-time relationships andadjusting the volume swap configuration, copy services manager 614disables any continuous synchronous copy requirements betweenpoint-in-time target volume 608 and point-in-time target volume 610. Ifany of the conditions determined by copy services manager 614 arenegative, then copy services manager 614 establishes both point-in-timecopy relationships but does not disable any continuous synchronous copyrequirements between point-in-time target volume 608 and point-in-timetarget volume 610. Once the volume swap configuration is adjusted, copyservice manager 614 may load or pass the volume swap configuration toIOS/device driver 616 for implementation.

If copy services manager 614 receives a request to withdraw one or morepoint-in-time copy relationships, copy services manager 614 determineswhether the one or more point-in-time copy target volumes, point-in-timetarget volume 608 or 610, are part of the volume swap configuration. Ifeither point-in-time target volume 608 or 610 are part of the volumeswap configuration, then copy services manager 614 removes thepoint-in-time copy relationship between source volume 602 andpoint-in-time target volume 608 as well as the point-in-time copyrelationship between target volume 604 and point-in-time target volume610 from the volume swap configuration as well as the volume swaprelationship between point-in-time target volume 608 and point-in-timetarget volume 610 from the volume swap configuration.

In FIG. 6B, when IOS/device driver 616 in server 606 receives a commandor detects an error in writing to or reading from either source volume602 or point-in-time target volume 608, IOS/device driver 616 initiatesa volume swap. IOS/device driver 616 then terminates the continuoussynchronous copy between source volume 602 and target volume 604.IOS/device driver 616 then directs all subsequent I/O to target volume604 and point-in-time target volume 610. In addition, all therequirements of a continuous synchronous copy relationship betweenpoint-in-time target volume 608 and point-in-time target volume 610,such as significant set-up time, establishment of the continuoussynchronous copy relationship, additional resources on and between thestorage system, additional planning and monitoring by the operator (orapplication), and additional bandwidth for the continuous synchronouscopy paths, are no longer required and a cost savings may be realized.

The copyset formed by source volume 602, target volume 604,point-in-time target volume 608 and point-in-time target volume 610 maybe just one of what may be any number of copysets in a data processingsystem and may be all part of a singular session. When IOS/device driver616 receives a command or detects an error in writing to or reading fromeither source volume 602 or point-in-time target volume 608, IOS/devicedriver 616 may also terminate other copy relationships in the sessionbased on the established copysets.

Thus, the illustrative embodiments provide a mechanism for changingcurrent implementations for volume swapping from a source volume to atarget volume through a copy services manager recognizing that thesource volume and target volume of a synchronous continuous copyrelationship are both sources of respective pending point-in-time copyrelationships that are write-inhibited. With this knowledge, the copyservices manager will add the point-in-time copy target volumes into thevolume swapping configuration and puss the new configuration to eitheran Input/Output Supervisor (IOS), a device driver, or the like, prior toestablishing the point-in-time copy relationships. Using the newconfiguration may make a point-in-time copy target eligible for a volumeswapping operation. When the point-in-time copy relationships arewithdrawn, the copy services manager will pass a new configuration tothe IOS/device driver that has the point-in-time copy target volumeremoved making the volumes no longer volume swapping capable.

As will be appreciated by one skilled in the art, the present inventionmay be embodied as a system, method, or computer program product.Accordingly, aspects of the present invention may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the present invention may take the form of a computer programproduct embodied in any one or more computer readable medium(s) havingcomputer usable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablemedium would include the following: an electrical connection having oneor more wires, a portable computer diskette, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CDROM), an optical storage device, amagnetic storage device, or any suitable combination of the foregoing.In the context of this document, a computer readable storage medium maybe any tangible medium that can contain or store a program for use by orin connection with an instruction execution system, apparatus, ordevice.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, in abaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Computer code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, radio frequency (RF), etc., or anysuitable combination thereof.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk™, C++, or the like, and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer, or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to the illustrativeembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or black diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions thatimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus, or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

Referring now to FIGS. 7 and 8, these figures provide flowchartsoutlining example operations of volume swapping point-in-time read-onlytarget volumes. FIG. 7 depicts a flowchart outlining example operationsperformed by a copy services manager in adding point-in-time copyrelationships to a data processing system in accordance with anillustrative embodiment. As the operation begins, the copy servicesmanager receives a request to establish a continuous synchronous copyrelationship between a source volume and a target volume that arecoupled to a server (step 702). The copy services manager establishes aconfiguration between the source volume and the target volume such that,when an application on the server writes to the source volume, the samedata is written to the target volume before control is returned to theapplication (step 704). Thus, the data on the target volume is the sameas the data on the source volume. The copy services manager then addsboth the source volume and the target volume to a volume swapconfiguration that identifies the pair of volumes as a continuoussynchronous copy pair and that that target volume is the volume to beswapped to if a command is received to perform a volume swap operationor an error is detected writing to or reading from the source volumesuch that a volume swap is performed (step 706).

As the operation continues, the copy service manager receives a requestto establish a first point-in-time copy relationship (step 708). Thecopy services manager then determines whether the first point-in-timecopy target volume associated with the source volume is a candidate fora non-continuous synchronous copy volume swap relationship. In order tomake this determination, the copy services manager determines whether atarget of the first point-in-time copy relationship is target writeinhibited (step 710). If at step 710 the target of the firstpoint-in-time copy relationship is target write inhibited, then the copyservices manager determines whether the source of the firstpoint-in-time copy relationship is a continuous synchronous copy source(step 712). If at step 712 the source of the first point-in-time copyrelationship is a continuous synchronous copy source, then the copyservices manager determines whether the target of the continuoussynchronous copy is either the source of the already established secondpoint-in-time copy relationship or is intended to be a source of thesecond point-in-time copy relationship (step 714). If at step 714 thetarget of the continuous synchronous copy is the source or intendedsource of the second point-in-time copy relationship, then the copyservices manager determines whether the source of the firstpoint-in-time copy relationship is part of a volume swap configuration(step 716).

If at step 716 the source of the first point-in-time copy relationshipis part of volume swap configuration, then the copy services manager mayadd the point-in-time copy relationship between the source volume and afirst point-in-time target volume as well as the point-in-time copyrelationship between the target volume and the second point-in-timetarget volume to the volume swap configuration (step 718). Adding thepoint-in-time copy relationships to the volume swap configuration by thecopy services manager is purely for providing additional information tothe IOS, device driver, or the like, as the point-in-time relationshipsare not used during a volume swap. By adding the point-in-timerelationships to the volume swap configuration, the IOS, device driver,or the like, is made aware of the existence of the point-in-time copyrelationships and is therefore a purely optional step.

The copy services manager then adds the volume swap relationship betweenthe first point-in-time target volume and the second point-in-timetarget volume to the volume swap configuration with a flag setindicating that the IOS, device driver, or the like, need not verify ormonitor any continuous synchronous copy relationship between the firstpoint-in-time target volume and the second point-in-time target volume(step 720). After the volume swap relationship has been added to thevolume swap configuration at step 720 and prior to establishing bothpoint-in-time copy relationships, the copy services manager specifies apoint-in-time copy consistency group option (step 722). Thepoint-in-time consistency option causes the source volume to be longbusied or uninterruptable while the copy services manager establishesboth point-in-time copy relationships between source volume and thefirst point-in-time target volume as well as between the target volumeand the second point-in-time target volume (step 724).

In addition to establishing the point-in-time relationships andadjusting the volume swap configuration, the copy services managerdisables any continuous synchronous copy requirements between the firstpoint-in-time target volume and the second point-in-time target volume(step 726), with the operation ending thereafter. If any of theconditions at step 710, 712, 714, or 716 are not met, then the copyservices manager establishes both point-in-time copy relationships (step728) and does not disable any continuous synchronous copy requirementsbetween the first point-in-time target volume and the secondpoint-in-time target volume (step 730), with the operation endingthereafter. Once the volume swap configuration is adjusted, the copyservice manager may load or pass the volume swap configuration to anInput/Output Supervisor (IOS), a device driver, or the like forimplementation.

FIG. 8 depicts a flowchart outlining example operations performed by acopy services manager in withdrawing point-in-time copy relationships toa data processing system in accordance with an illustrative embodiment.As the operation begins, the copy services manager receives a request towithdraw one or more point-in-time copy relationships (step 802). Thecopy services manager determines whether the one or more point-in-timecopy target volumes are part of a volume swap relationship in the volumeswap configuration (step 804). If at step 804 one or more of thepoint-in-time target volumes are part of a volume swap relationship inthe volume swap configuration, then the copy services manager removesthe volume swap relationship from the volume swap configuration (step806). Then the copy services manager withdraws the one or morepoint-in-time copy relationships (step 808), with the operation endingthereafter. If at step 804 none of the one or more point-in-time targetvolumes are part of a volume swap relationship in the volume swapconfiguration, then the copy services manager withdraws the one or morepoint-in-time copy relationships (step 808), with the operation endingthereafter. Once the volume swap configuration is adjusted, the copyservice manager may load or pass the volume swap configuration to anInput/Output Supervisor (IOS), a device driver, or the like forimplementation.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

Thus, the illustrative embodiments provide mechanisms for a mechanismfor changing current implementations for volume swapping from a sourcevolume to a target volume to have a copy services manager recognize thatthe source volume and target volume of a synchronous continuous copyrelationship are both sources of respective pending point-in-time copyrelationships. With this knowledge, the copy services manager will addthe point-in-time copy target volumes into the volume swappingconfiguration and pass the new configuration to either an Input/OutputSupervisor (IOS), a device driver, or the like, prior to invoking thepoint-in-time copy. Using the new configuration may make a point-in-timecopy target eligible for a volume swapping operation. When thepoint-in-time copy relationships are withdrawn, the copy servicesmanager will load a new configuration that has the point-in-time copytarget volume removed making the volumes no longer volume swappingcapable.

As noted above, it should be appreciated that the illustrativeembodiments may take the form of an entirely hardware embodiment, anentirely software embodiment or an embodiment containing both hardwareand software elements. In one example embodiment, the mechanisms of theillustrative embodiments are implemented in software or program code,which includes but is not limited to firmware, resident software,microcode, etc.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, etc.) can be coupled to the system eitherdirectly or through intervening I/O controllers. Network adapters mayalso be coupled to the system to enable the data processing system tobecome coupled to other data processing systems or remote printers orstorage devices through intervening private or public networks. Modems,cable modems and Ethernet cards are just a few of the currentlyavailable types of network adapters.

The description of the present invention has been presented for purposesof illustration and description, and is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain theprinciples of the invention, the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

1. A method, in a data processing system, for adding point-in-time copyrelationships to the data processing system, the method comprising:receiving, by a copy services manager, a request to establish a firstpoint-in-time copy relationship; determining, by the copy servicesmanager, whether a first point-in-time target volume is a candidate fora non-continuous synchronous copy volume swap relationship; adding, bythe copy services manager, a volume swap relationship between the firstpoint-in-time target volume and a second point-in-time target volume toa volume swap configuration in response to identifying that the firstpoint-in-time target volume as the candidate for the non-continuoussynchronous copy volume swap relationship: establishing, by the copyservices manager, the first point-in-time copy relationship and a secondpoint-in-time copy relationship in the data processing system;disabling, by the copy service manager, any continuous synchronous copyrequirements of the volume swap relationship between the firstpoint-in-time target volume and the second point-in-time target volume.2. The method of claim 1, wherein the volume swap relationship comprisesa flag indicating that at least one of an input/output supervisor or adevice driver need not verify or monitor any continuous synchronous copyrelationship between the first point-in-time target volume and thesecond point-in-time target volume.
 3. The method of claim 1, furthercomprising: adding, by the copy services manager, the firstpoint-in-time copy relationship between a source volume and the firstpoint-in-time target volume and the second point-in-time copyrelationship between a target volume and the second point-in-time targetvolume to the volume swap configuration.
 4. The method of claim 1,wherein determining whether the first point-in-time target volume is thecandidate for the non-continuous synchronous copy volume swaprelationship comprises: determining, by the copy services manager,whether the first point-in-time target volume of the first point-in-timecopy relationship is target write inhibited; determining, by the copyservices manager, whether a source volume of the first point-in-timecopy relationship is a source of a continuous synchronous copyrelationship in response to determining that the first point-in-timetarget volume is target write inhibited; determining, by the copyservices manager, whether a target volume of the continuous synchronouscopy relationship is either a source of an already established secondpoint-in-time copy relationship or an intended source of the secondpoint-in-time copy relationship in response to determining that thesource volume of the first point-in-time copy relationship is the sourceof the continuous synchronous copy relationship; and determining, by thecopy services manager, that the source volume of the first point-in-timecopy relationship is part of the volume swap configuration in responseto determining that the target volume of the continuous synchronous copyrelationship is either the source of the already established secondpoint-in-time copy relationship or the intended source of the secondpoint-in-time copy relationship.
 5. The method of claim 1, furthercomprising: specifying, by the copy services manager, a point-in-timecopy consistency group option, wherein the point-in-time consistencyoption causes a source volume to be uninterruptable while the copyservices manager establishes the first point-in-time copy relationshipbetween the source volume and the first point-in-time target volume andthe second point-in-time copy relationship between a target volume andthe second point-in-time target volume.
 6. The method of claim 1,further comprising: receiving, by the copy services manager, a requestto establish a continuous synchronous copy relationship between a sourcevolume and a target volume; establishing, by the copy services manager,a configuration between the source volume and the target volume; andadding, by the copy service manager, the continuous synchronous copyrelationship between the source volume and the target volume to thevolume swap configuration.
 7. The method of claim 6, wherein, by addingthe continuous synchronous copy relationship between the source volumeand the target volume to the volume swap configuration, the sourcevolume and the target volume are identified as a pair of volumes in thecontinuous synchronous copy relationship.
 8. The method of claim 6,wherein at least one of a input/output supervisor or a device driverdirects input/output commands to the target volume in response to acommand being received to perform a volume swap operation or in responseto an error being detected writing to or reading from the source volumeor reading from the first point-in-time target volume that initiates thevolume swap operation.
 9. The method of claim 1, wherein, when anapplication on the data processing system writes data to the sourcevolume, the same data is written to the target volume before control isreturned to the application.
 10. The method of claim 1, furthercomprising: receiving, by the copy services manager, a request towithdraw one or more point-in-time copy relationships; determining, bythe copy services manager, whether targets of the one or morepoint-in-time copy relationships are part of the volume swapconfiguration; removing, by the copy services manager, the volume swaprelationship between the first point-in-time target volume and thesecond point-in-time target volume from the volume swap configuration inresponse to the targets of the one or more point-in-time copyrelationships being part of the volume swap configuration; andwithdrawing, by the copy services manager, the first point-in-time copyrelationship and the second point-in-time copy relationship.
 11. Acomputer program product comprising a computer readable storage mediumhaving a computer readable program stored therein, wherein the computerreadable program, when executed on a computing device, causes thecomputing device to: receive a request to establish a firstpoint-in-time copy relationship; determine whether a first point-in-timetarget volume is a candidate for a non-continuous synchronous copyvolume swap relationship; add a volume swap relationship between thefirst point-in-time target volume and a second point-in-time targetvolume to a volume swap configuration in response to identifying thatthe first point-in-time target volume as the candidate for thenon-continuous synchronous copy volume swap relationship; establish thefirst point-in-time copy relationship and the second point-in-time copyrelationship in the data processing system; disable any continuoussynchronous copy requirements of the volume swap relationship betweenthe first point-in-time target volume and the second point-in-timetarget volume.
 12. The computer program product of claim 11, wherein thevolume swap relationship comprises a flag indicating that at least oneof an input/output supervisor or a device driver need not verify ormonitor any continuous synchronous copy relationship between the firstpoint-in-time target volume and the second point-in-time target volume.13. The computer program product of claim 11, wherein the computerreadable program further causes the computing device to: add the firstpoint-in-time copy relationship between a source volume and the firstpoint-in-time target volume and the second point-in-time copyrelationship between a target volume and the second point-in-time targetvolume to the volume swap configuration.
 14. The computer programproduct of claim 11, wherein the computer readable program to determinewhether the first point-in-time target volume is the candidate for thenon-continuous synchronous copy volume swap relationship further causesthe computing device to determine whether the first point-in-time targetvolume of the first point-in-time copy relationship is target writeinhibited; determine whether a source volume of the first point-in-timecopy relationship is a source of a continuous synchronous copyrelationship in response to determining that the first point-in-timetarget volume is target write inhibited; determine whether a targetvolume of the continuous synchronous copy relationship is either asource of an already established second point-in-time copy relationshipor an intended source of the second point-in-time copy relationship inresponse to determining that the source volume of the firstpoint-in-time copy relationship is the source of the continuoussynchronous copy relationship; and determine that the source volume ofthe first point-in-time copy relationship is part of the volume swapconfiguration in response to determining that the target volume of thecontinuous synchronous copy relationship is either the source of thealready established second point-in-time copy relationship or theintended source of the second point-in-time copy relationship.
 15. Thecomputer program product of claim 11, wherein the computer readableprogram further causes the computing device to: specify a point-in-timecopy consistency group option, wherein the point-in-time consistencyoption causes a source volume to be uninterruptable while the copyservices manager establishes the first point-in-time copy relationshipbetween the source volume and the first point-in-time target volume andthe second point-in-time copy relationship between a target volume andthe second point-in-time target volume.
 16. An apparatus, comprising: aprocessor; and a memory coupled to the processor, wherein the memorycomprises instructions which, when executed by the processor, cause theprocessor to; receive a request to establish a first point-in-time copyrelationship; determine whether a first point-in-time target volume is acandidate for a non-continuous synchronous copy volume swaprelationship; add a volume swap relationship between the firstpoint-in-time target volume and a second point-in-time target volume toa volume swap configuration in response to identifying that the firstpoint-in-time target volume as the candidate for the non-continuoussynchronous copy volume swap relationship; establish the firstpoint-in-time copy relationship and the second point-in-time copyrelationship in the data processing system; disable any continuoussynchronous copy requirements of the volume swap relationship betweenthe first point-in-time target volume and the second point-in-timetarget volume.
 17. The apparatus of claim 16, wherein the volume swaprelationship comprises a flag indicating that at least one of aninput/output supervisor or a device driver need not verify or monitorany continuous synchronous copy relationship between the firstpoint-in-time target volume and the second point-in-time target volume.18. The apparatus of claim 16, wherein the instructions further causethe processor to: add the first point-in-time copy relationship betweena source volume and the first point-in-time target volume and thepoint-in-time copy relationship between a target volume and the secondpoint-in-time target volume to the volume swap configuration.
 19. Theapparatus of claim 16, wherein the instructions to determine whether thefirst point-in-time target volume is the candidate for thenon-continuous synchronous copy volume swap relationship further causethe processor to: determine whether the first point-in-time targetvolume of the first point-in-time copy relationship is target writeinhibited; determine whether a source volume of the first point-in-timecopy relationship is a source of a continuous synchronous copyrelationship in response to determining that the first point-in-timetarget volume is target write inhibited; determine whether a targetvolume of the continuous synchronous copy relationship is either asource of an already established second point-in-time copy relationshipor an intended source of the second point-in-time copy relationship inresponse to determining that the source volume of the firstpoint-in-time copy relationship is the source of the continuoussynchronous copy relationship; and determine that the source volume ofthe first point-in-time copy relationship is part of the volume swapconfiguration in response to determining that the target volume of thecontinuous synchronous copy relationship is either the source of thealready established second point-in-time copy relationship or theintended source of the second point-in-time copy relationship.
 20. Theapparatus of claim 16, wherein the instructions further cause theprocessor to: specify a point-in-time copy consistency group option,wherein the point-in-time consistency option causes a source volume tobe uninterruptable while the copy services manager establishes the firstpoint-in-time copy relationship between the source volume and the firstpoint-in-time target volume and the second point-in-time copyrelationship between a target volume and the second point-in-time targetvolume.